New moving image compression methods are based on a resolution of the image content into what are referred to as image objects with arbitrary edging. The individual image objects are separately encoded in various video object planes (what are referred to as VOPs), and are transmitted and decoded in the receiver and again "combined". Traditional image compression methods are based on a resolution of the entire image into quadratic image blocks. This principle can also be accepted in the object-based methods. However, problems arise in the encoding of the image blocks that are located at the edge of the respective image object since the object edging usually does not coincide with the block edges. What is referred to as a motion-compensated prediction of these edge blocks is especially critical in this context.
There are a number of different search strategies for the motion estimation and the motion compensation. What is referred to as the "block matching method" is usually utilized for block-based image compression methods. It is based thereon that the image block to be encoded is compared with same-sized blocks of a reference image. One of the reference image blocks is located at the same position as the image block to be encoded; the other reference image blocks are topically shifted compared to it. Given a large search area in the horizontal and vertical directions, a great number of search positions thus derive, so that correspondingly, many block comparison ("matchings") must also be implemented given what is referred to as a complete search ("full search"). The sum of the absolute differences of the encoding information that is respectively allocated to each picture element is usually employed as a criterion for the match quality between the block to be respectively encoded and the reference block.
What is to be understood by encoding information in the framework of this document is, for example, the luminance information with which a luminance value that a picture element exhibits is respectively described or, too, a color information, i.e. the chrominance value allocated to the respective picture element.
It is known in the motion compensation from the publication ISO/IEC JTC1/SC29/WG11, Coding of Moving Pictures and Associated Audion Information, MPEG 96/N1380. MPEG5 Video Verification Model, Version 4.0, pages 31 through 35, Chicago, October 1996, to implement what is referred to as a padding in the framework of the motion compensation, whereby the padding given the method from the ISO publication occurs over the entire area of the reference image RB that does not belong to the image object BO.
The block-based image encoding method MPEG 2 is known from the publication J. De Lameillieure and R. Schafer, MPEG-2-Bildcodierung fur das digitale Fernsehen, Fernsehund Kino-Technik, Volume 48, No. 3, pp. 99-107, 1994. The publication Xiaolin Wu and Yonggang Fang, A Segmentation-Based Predictive Multiresolution Image Coder, IEEE Transactions on Image Processing, Vol. 4, No. 1, pp. 34-46, January 1995, discloses a method for segmentation of image objects from an image.